Method and apparatus for automatic implantable medical lead recognition and configuration

ABSTRACT

An automated identification and configuration system for use with an implantable medical device (IMD) is disclosed. The system includes a first communication circuit that is attached to, or otherwise carried by, a detachable component associated with the IMD such as a medical lead. The communication circuit stores data such as model numbers, serial numbers, technical data, and/or calibration information that describes the additional component. This information may be transferred by the first communications circuit to a second communications circuit that is external to the additional component. This transferred data can be used to automatically configure the internal circuitry and connection functions of the IMD to properly interface with, and support, the additional component. For example, the data can be used to automatically adjust amplifier gains or other sensor circuitry, or to configure a connector block to properly couple to the component. The data may further be entered into a patient record on an external programmer, or may be transferred to a central storage location to be generally accessible to health care providers. In one embodiment, the first communication circuit is a passive RF transponder. This first communication circuit may include a receiver as well as a transmitter to allow the circuit to programmably receive data at the time of component manufacture.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to implantable medicaldevices; and, more particularly, to a method and apparatus toautomatically identify multiple leads and their proper connection to animplantable medical device such as a pacemaker orcardioverter/defibrillator.

[0003] 2. Background Art

[0004] An implantable intravascular lead assembly is often implantedwithin a patient's body to provide electrical stimulation to the heart.Such lead assemblies may include one or more electrical conductors thatare adapted to be suitably connected to a source of electrical energy,which may be a pacemaker or cardioverter/defibrillator. The electricalconductor, in turn, includes an electrode tip that engages theendocardial or epicardial tissue of the heart to provide stimulation andsensing capabilities. The lead assembly may be intravenously insertedthrough a body vessel, such as a vein, into one or more cardiacchambers, or alternatively, attached to the epicardial surface of theheart. The conductor is sealed from body fluids by a biocompatible andbio-stable insulating material.

[0005] In a typical lead assembly, the electrode tip is firmly lodgedin, and permanently secured to, the endothelial lining or epicardialsurface of the heart. These lead assemblies are referred to as anendocardial or epicardial lead, respectively. Some examples ofconventional endocardial and epicardial leads may be found in U.S. Pat.No. 3,348,548 to Chardack, U.S. Pat. No. 3,754,555 to Schmitt, U.S. Pat.No. 3,814,104 to Irnich et al., U.S. Pat. No. 3,844,292 to Bolduc, U.S.Pat. No. 3,974,834 to Kane, U.S. Pat. No. 5,246,014 to Williams, andU.S. Pat. No. 5,397,343 to Smits. A representative defibrillation leadis described in U.S. Pat. No. 6,178,355 to Williams.

[0006] With the increased use of multi-chamber pacemakers anddefibrillators such as those that provide bi-atrial or bi-ventricularpacing capabilities, multiple leads are required to deliver electricalstimulation to various locations within the heart. With the use ofmultiple leads that are positioned within one or more small vessels ofthe body, it has become even more important to minimize lead and leadconnector size. As leads become smaller, it becomes increasinglydifficult to mark leads with the appropriate identification, includingmanufacturer identification and/or lead model and serial numbers. Thismay make it more difficult for a physician to determine which lead is tobe inserted into a given port of an implantable medical device (IMD)during an implant procedure.

[0007] One solution to providing marking information on lead systems isdescribed in U.S. Pat. No. 5,824,030 to Yang. This patent discloses asingle-pass transvenous lead for atrial sensing and pacing, ventricularsensing and pacing, as well as for ventricular and atrialdefibrillation. Visual indicators are provided on the lead to identifywhich one of several distal electrode pairs are being used.

[0008] Another solution to properly configuring the leads of an IMD isdisclosed in U.S. Pat. No. 5,374,279 to Duffin. The described medicalelectrical pulse generator includes a switchable connector assembly. Theconnector assembly is provided with connector bores that are eachadapted to receive a medical electrical lead. Electrical connectorslocated within the bores are arranged such that interconnection of thepulse generator circuitry and the configuration of the electrodes on theleads and/or housing of the device can be altered by means of connectorpins.

[0009] Yet another method of attaching multiple electrode leads to anIMD is described in U.S. Pat. No. 4,628,934 to Pohndorf. The '934 patentdescribes an electronic electrode switching circuit that minimizes thenumber of feedthroughs from a pacer case to a pacer neck that are neededto couple to the pacing lead electrodes. These feedthroughs can beselectively connected to a desired electrode by the physician at thetime of initial implantation or any time thereafter. The electronicconnection to a feedthrough may be dedicated to a single electrode orelectrode pair, or alternatively, the electrodes may be electronicallysampled by circuitry in the pacer. The electrode switching circuit maybe located in the pacer neck, in an adapter between the pacer neck and amultielectrode lead, or in a multielectrode lead.

[0010] Another method for automatically configuring the multiple leadsof an IMD is described in U.S. Pat. No. 6,085,118 to Hirschberg. The'118 patent describes an implantable cardiac stimulator with at leasttwo terminals. Each terminal is connectable to an implantable electrodefor delivering stimulation pulses to a heart, and/or for sensing cardiacactivity signals. The stimulator also has a switch and a control unitwhich operates the switch, so that one or both terminals are connectableto the pulse generator. The control unit identifies a position statusfor at least one of the electrodes in response to a signal received atthe time of implantation. Although the control unit may use a signalfrom an electrode to configure the switch, premature sensed events,artifacts and/or EMI may cause the control unit to incorrectly configurethe system.

[0011] Another identification system is described in U.S. Pat. No.5,300,120 to Knapp, which involves a passive transponder that may beencoded with a binary value that may be up to sixty-four bits long. Thisvalue may be read with a hand-held electromagnetic device that islocated outside the body and in proximity to the transponder. Theencoded information may include patient demographics, implant data, andmanufacturer information.

[0012] Another similar mechanism for remotely monitoring device data isdescribed in U.S. Pat. No. 5,626,630 to Markowitz. The disclosedtelemetry system includes a remote monitoring station, a repeater wornexternally by a patient, and a quasipassive transponder attached to adevice implanted in the patient. The remote monitoring stationcommunicates to the repeater to initiate an interrogation routinebetween the repeater and the transponder to extract patient conditioninformation from the implanted device. When the repeater receives thecondition information, it relays it to the remote monitoring station.The disclosed system does not automatically identify leads, calibratelead-based sensors, or automatically configure leads and/or sensors toan IMD.

[0013] U.S. Pat. No. 5,833,603 to Kovacs describes another system forsensing one or more physiological signals within a living body tomeasure optical, mechanical, chemical, and/or electrochemicalproperties. The system includes a transponder for wirelesslytransmitting data corresponding to the sensed parameter values to aremote reader. Disclosed embodiments utilize temperature sensors, strainsensors, pressure sensors, magnetic sensors, acceleration sensors,ionizing radiation sensors, acoustic wave sensors, chemical sensors, andphotosensors. The disclosed system does not include means toautomatically identify or configure leads, or to calibrate thelead-based sensors.

[0014] Another mechanism for identifying information related to theconfiguration of an IMD is disclosed in U.S. Pat. No. 5,423,334 toJordan. The disclosed system provides a characterization tag forattachment to the IMD. The tag circuitry is selectively loaded to storedata describing the IMD, and may be read by a probe located outside thebody. The system does not store lead identification or configurationinformation.

[0015] Yet another system for storing and transmitting deviceinformation is described in U.S. Pat. No. 5,252,962 to Urbas. Thedisclosed device includes a sensor for use in transmitting a parametersuch as temperature from within a living body to a device that islocated outside the body. The IMD includes a programmable memory tostore user ID data.

[0016] While the above publications teach various improvements to theart, they do not address the problem of identifying and configuringmultiple leads and/or other implantable devices for use with an IMD.

SUMMARY OF THE INVENTION

[0017] It is a principal object of the present invention to provide animproved interface between conventional lead systems and IMDs.

[0018] Another object is to provide a system and method forautomatically identifying leads and for enabling the proper connectionof the identified leads to an IMD.

[0019] Another object is to provide a system and method forautomatically receiving sensor calibration information for lead-basedsensors.

[0020] Yet another object is to provide a system and method forautomatically calibrating lead-based sensors.

[0021] Another object is to provide an IMD that automatically configuresconnections between one or more leads and respective IMD ports.

[0022] An additional object is to provide a connector block forelectrically and mechanically coupling multiple leads or sensors to anelectrical source of energy, such as a pacemaker, defibrillator or neurostimulator.

[0023] Yet another object is to provide a system for use with an IMDthat allows an additional component of the IMD to be automaticallyidentified for purposes of system configuration.

[0024] It is a further object to provide a system for use with an IMDthat stores patient data that may be transferred to a central locationfor use in performing diagnosis and therapy.

[0025] The current system and method addresses these and otherobjectives by providing a system for use with an active IMD(hereinafter, “IMD”) such as a pacing device, or another externaldevice. The system is capable of automatically identifying one or moreadditional implantable medical devices such as leads that may beassociated with the IMD. In one embodiment, the invention includes afirst communication circuit that is attached to, or integrated within, alead. The communication circuit stores data such as model and serialnumbers, technical information, and calibration data. At the time ofimplant or sometime thereafter, information stored by the firstcommunication circuit may be transferred to a second communicationscircuit that is external to the lead. The second communications circuitmay reside within the IMD, an external programmer, a personal datamanagement (PDM) unit, or within any other unit such as a PersonalDigital Assistant (PDA) that is located within a predetermined range ofthe first communication circuit. This transferred data can be used bothto indicate the presence of the lead, and to identify lead type. Suchinformation can be used, for example, to automatically configure theconnector block of the IMD to properly couple to the lead. The data canfurther be used to automatically adjust amplifier gains or othercircuitry associated with the lead. The data may be entered into apatient record on an external programmer, or may be transferred to acentral storage location for use by health care providers whenperforming diagnosis and therapy associated with the IMD.

[0026] In another embodiment, the data provided by the firstcommunications circuit includes identification and calibrationinformation concerning additional components of the system. For example,physiologic sensors carried on the leads may be identified so that theIMD can enable and calibrate internal circuitry to receive thephysiologic signals. This allows certain functions within the IMD toautomatically be enabled only when a component is present in the systemso that power can otherwise be conserved. Any other components of an IMDmay be identified and calibrated by using a communication circuitaccording to the current invention. This may include implantable devicessuch as pluggable antennas, electrodes that can be selectively coupledto the IMD case, and any other types of components that may beselectively added to the system.

[0027] According to one aspect of the system, the first communicationcircuit may be a passively-powered RF transponder. The transponderreceives power from an external source. Ultrasonic, optical, andelectromagnetic power may be used to power the first communicationcircuit. In another embodiment, the first communication circuit mayreceive power from its host unit, such as via the conductors of a lead.According to another aspect of the system, the first communicationcircuit may include a receiver as well as a transmitter to receive datasignals from an external source. This allows the first communicationcircuit to be programmed with identification, calibration, and otherdata at the time of component manufacture.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028]FIG. 1 is a schematic view of an implantable medical device (IMD)implanted within a body.

[0029]FIG. 2 is a side cutaway view of an exemplary in-line connectorassembly at line 2-2 of FIG. 1 FIG. 3 is a side perspective view of oneembodiment of passive transponder of FIG. 2.

[0030]FIG. 4 is a side perspective view illustrating a sealedtransponder coupled to a lead.

[0031]FIG. 5 is a system block diagram of one embodiment of an IMD thatmay utilize the current invention.

[0032]FIG. 6 is a circuit block diagram illustrating in more detailexemplary components of the transponder and transmitter/receiver circuitof FIG. 5.

[0033]FIG. 7 is a system block diagram illustrating additionalembodiments of the present invention.

[0034]FIG. 8 is a circuit diagram illustrating a transponder coupled tothe therapy output energy source of an IMD.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035]FIG. 1 is a schematic view of an implantable medical device (IMD)12 implanted within a body. Leads 14 and 15 are shown coupled to theconnector assembly 20 of IMD 12 using one or more feedthroughs. IMD 12,which may be implanted near a human heart 16 or at another location inthe body, may be a pacemaker, cardioverter/defibrillator, drug deliverydevice, brain stimulator, gastric stimulator, nerve stimulator, or anyother implantable device. For example, implantable medical device 12 maybe an implantable cardiac pacemaker such as that described in U.S. Pat.No. 5,158,078 to Bennett et al., U.S. Pat. No. 5,312,453 to Shelton etal., or U.S. Pat. No. 5,144,949 to Olson et al. Alternatively, IMD 12may be a pacemaker-cardioverter-defibrillator (PCD) such as thosedescribed in U.S. Pat. No. 5,545,186 to Olson et al., U.S. Pat. No.5,354,316 to Keimel, U.S. Pat. No. 5,314,430 to Bardy, U.S. Pat. No.5,131,388 to Pless, or U.S. Pat. No. 4,821,723 to Baker, et al. As yetanother example, IMD 12 may be an implantable neurostimulator or musclestimulator such as those disclosed in U.S. Pat. No. 5,199,428 to Obel etal., U.S. Pat. No. 5,207,218 to Carpentier et al., or U.S. Pat. No.5,330,507 to Schwartz. The IMD may also be an implantable monitoringdevice such as that disclosed in U.S. Pat. No. 5,331,966 to Bennett etal., wherein all of the foregoing patents are incorporated by referenceherein in their respective entireties.

[0036]FIG. 2 is a side cutaway view of an exemplary in-line connectorassembly 20 at line 2-2 of FIG. 1. The connector assembly is showncoupled to a proximal end of lead 14. Connector assembly 20 employs a“setscrewless” lead retainer, and a stepped lumen 202 that receives aconnector pin mounted to the proximal end of lead 14. The connector pinincludes two conductive connector surfaces 208 and 210, and twoinsulative areas 212 and 214. Insulative areas 212 and 214 are eachprovided with a plurality of sealing rings 218 and 220 to seal lumen 202against fluid entry and to provide a seal intermediate conductive areas208 and 210. Conductive area 208 may take the form of a metallic,cylindrical pin. Conductive area 210 is illustrated as a metal cylinder.

[0037] Connector assembly 20 is shown mounted to the outer enclosure 222of IMD 12. Connection between the implantable pacemaker and the lead 14is made by means of spring members 224 and 226, which are mounted inconductive ferrules 228 and 230, respectively. Ferrules 228 and 230 aremetal cylinders having central bores and associated internalcircumferential grooves that retain the spring members 224 and 226. Wheninserted, spring members 224 and 226 provide for electrical coupling.Ferrules 228 and 230 are coupled to feedthrough wires 232 and 234 bymeans of wires 236 and 238, respectively.

[0038] The proximal end of lead 14 is shown provided with a cylindricalplastic member 240 that includes a circumferential groove 242 that mateswith a deflectable beam lead retainer 244 provided at the distal end ofthe connector assembly 20. In the embodiment shown, the lead retainer244 is integrally molded to connector module 20, although the retainermay also be fabricated separately. Surrounding the deflectable leadretainer 244 is an insulative boot 246, which in turn, is surrounded bya suture 248 that acts as a lock to prevent expansion of the deflectablebeam retainer 244 to retain lead 14 within connector assembly 20.

[0039] The proximal end of lead 14 further includes a first and secondcommunication circuit, which in this embodiment are a passivetransponder 262 adapted to communicate with transmitter/receiver 260,respectively. This communication may be facilitated by RF transmissionsas substantially described in U.S. Pat. Nos. 4,730,188, 5,041,826, and5,166,676 to Milheiser, U.S. Pat. No. 5,025,550 to Zirbes, or U.S. Pat.Nos. 5,223,851 and 5,281,855 to Hadden, incorporated herein by referencein their entireties. As noted in the foregoing patents, such passivetransponders include an energy coupler for wirelessly couplingelectromagnetic, ultrasonic, or optical energy, for example, that isprovided by a remote energy source. In one embodiment of the currentinvention, the energy source is provided by transmitter/receiver 260.Energy may also be provided by another circuit in the IMD. Passivetransponder 262 further includes a communication circuit powered by theenergy received from the remote energy source, and that is adapted totransfer a signal indicative of identification data stored within thetransponder. This will be discussed further below.

[0040] It may be noted that the connector assembly 20 shown in FIG. 2 isexemplary only, and many other types of connector assemblies and leadconnector types including in-line or bifurcated lead connectors andconnector assembly configurations may be utilized.

[0041]FIG. 3 is a side perspective view of one embodiment of passivetransponder 262 of FIG. 2. The transponder includes a wire coil antenna106 encircling bobbin 108. This antenna may be tuned to the frequency ofthe carrier signal using an RLC tuned resonant circuit includingcapacitor 105 to allow for more efficient signal transmission. Thecenter of bobbin 108 includes a lumen 109 to receive a lead. Anintegrated circuit 102 containing RF receiver/transmitter circuitry maybe mounted on bobbin 108. A hermetic cylindrical cover (not shown inFIG. 3) seals the transponder 262 in a manner described in U.S. Pat. No.5,782,891 to Donders, incorporated herein by reference in its entirety.FIG. 3 further illustrates a surface acoustic wave (SAW) filter 104 tofilter signals transmitted by the RF receiver/transmitter circuitry in amanner described further below.

[0042]FIG. 4 is a side perspective view illustrating a sealedtransponder 262 coupled to lead 14. The sealed transponder 262 may beinserted under a connector sleeve (not shown in FIG. 4) and backfilledwith medical adhesive. It may be noted that the transponder of FIG. 3may be coupled to the lead in many other ways. For example, in anotherembodiment, the transponder may be fully integrated within the lead bodyinstead of being provided as a separate component.

[0043]FIG. 5 is a system block diagram of one embodiment of an IMD thatmay utilize the current invention. IMD 300 is provided with aninput/output circuit 320 to sense physiological signals and/or toprovide electrical stimulation to a patient. If IMD 300 is a pacemaker,input/output circuit 320 may provide all of the basic timing,stimulation and sensing functions of a DDD or DDDR of acommercially-available pacing device.

[0044] Input/output circuit 320 provides the control functions of theIMD. For example, digital controller/timer 330, which receives a clocksignal from crystal oscillator circuit 338, generates the appropriatetiming and control sequences for the rest of the IMD. Battery 318provides power for all the components of the IMD, and power-on-resetcircuit 336 defines an initial operating condition and also resets theoperative state of the device in response to detection of a low batterycondition. Reference mode circuit 326 generates stable voltage andcurrents references for the analog circuits within input/output circuit320.

[0045]FIG. 5 also illustrates leads 14 and 15 coupled to IMD 300.Additional leads\catheters such as exemplary lead 26 may further beimplanted within the body for sensing signals and/or for providingelectrical stimulation or drug therapy in a manner to be discussedbelow.

[0046] One or more of these leads may carry one or more electrodes. Lead14, which may be an atrial bipolar pacing lead, is shown carrying twoelectrodes 19 and 21 positioned in the right atrium of heart 16.Electrodes 19 and 21 may be used both to sense and pace the atrium in amanner well known in the art. Similarly, lead 15 represents aventricular bipolar lead that may carry two electrodes 23 and 25implanted in the right ventricle of the heart 16. As discussed above inconjunction with atrial lead 14, electrodes 23 and 25 may be used tosense and pace the ventricle in a manner well known in the art.

[0047] In addition to electrodes, one or more other types of sensors ofany type known in the art for sensing physiological signals may also becarried on one or more of the leads. For example, sensors may beprovided to measure oxygen saturation, change in pressure dP/dT,temperature, minute ventilation or respiration rate. Exemplary sensorsystems are described in U.S. Pat. No. 5,154,170 to Bennett et al., U.S.Pat. No. 5,144,524 to Reuter, U.S. Pat. No. 5,271,395 to Wahlstrand, andU.S. Pat. No. 4,485,813 to Anderson.

[0048] Analog signals sensed by any of the sensors and/or electrodes maybe provided to a programmable electronic switch such as selectioncircuit 361 to be described further below. The selected signals areprovided to sense amplifiers 360. The gain of sense amplifiers 360 maybe controlled via controller/timer circuit 330 via gain/energy control348. The amplified analog signals are received by controller/timercircuit, and provided to analog-to-digital converter (ADC) andmultiplexor circuit 328. The ADC digitizes the analog signals so thatthe signals may be stored and/or transferred to an external device suchas a programmer.

[0049] Transmission of signals to an external device is accomplished viaRF transmitter/receiver circuit 332 and a telemetry antenna 334. The RFtransmitter/receiver circuit 332 demodulates received downlink telemetrycommunications and transmits uplink telemetry data. An exemplary circuitfor demodulating and decoding downlink telemetry may correspond to thatdisclosed in U.S. Pat. No. 4,556,063, while uplink telemetry functionsmay be provided according to U.S. Pat. Nos. 5,127,404 and 4,374,382.Uplink telemetry capabilities will typically include the ability totransmit stored digital information as well as physiological signalssensed in real-time as described in the '404 patent. It may also becapable of transmitting marker signals indicating the occurrence ofsensed and paced depolarizations in the atrium and ventricle, asdisclosed in the cited '382 patent.

[0050] IMD 300 further includes a microcomputer circuit 302. Thiscircuit controls the operational functions of digital controller/timercircuit 330 via data and control bus 306 by specifying, for example,which timing intervals are employed for performing pacing and sensingfunctions. Microcomputer 302 may include a microprocessor 304 andassociated system clock 308 and on-board processor RAM and ROM 310 and312, respectively. In addition, microcomputer circuit 302 may include anadditional storage unit such as RAM/ROM circuit 314 to provideadditional memory capacity. Microprocessor 304 may be interrupt driven,operating in a reduced power consumption mode normally, and awakened inresponse to defined interrupt events, which may include sensedphysiological signals.

[0051] In addition to interfacing to microcomputer 302, controller/timer330 further interfaces directly or indirectly with a battery 318, anactivity sensor 30, a telemetry antenna 334, and various feedthroughs(not shown in FIG. 5) to the lead connector elements included inconnector assembly 20 discussed above. A piezoelectric crystal activitysensor 30 may be provided to generate electrical pressure wave signalsin response to sensed physical activity. The generated signal isprocessed by activity circuit 322, which, in turn, provides activitysignal 324 to digital controller/timer circuit 330. Activity circuit 322and associated activity sensor 30 may correspond to the circuit andsensor disclosed in U.S. Pat. No. 5,052,388 to Sivula et al.,incorporated herein by reference in its entirety.

[0052] IMD 300 also includes an output amplifier circuit 340 to provideelectrical stimulation to heart 16 via one or more of electrodes 23 and25 on lead 18V, as well as one or more of electrodes 19 and 21 locatedon lead 18A. In order to trigger generation of a ventricular pacing orV-PACE pulse, digital controller/timer circuit 330 generates a triggersignal on V-TRIG line 342. Similarly, in order to trigger an atrialpacing or A-PACE pulse, digital controller/timer circuit 330 generates atrigger pulse on A-TRIG line 344. The A-PACE and V-PACE pulse energiesmay be controlled in pulse width and/or amplitude by gain/energy control348 which receives a pace energy command signal from digitaltimer/controller circuit 330. The timing of pacing signals may becontrolled based on programmable rate-response features that take intoconsideration one or more measured physiological parameters as known inthe art. Digital controller/timer circuit 330 defines the pacing orescape intervals used to pace the atrium and ventricle using any of thesensing and timing mechanisms known in the art. The signals generated byoutput amplifier circuit may be provided to a programmable switch suchas selection circuit 341, which is programmed by controller/timer 330 ina manner to be discussed below.

[0053] In the current embodiment, controller/timer circuit is furthershown coupled to transmitter/receiver 380, which, in turn, is coupledvia connection 386 to RF antenna 260. This antenna transmits energy topassive transponder 262 carried on lead 14. The energy, which may beoptical, electromagnetic, or ultrasonic, for example, is used to powercircuitry within passive transponder 262 such that the transponderinitiates a data transfer operation to the transmitter/receiver 380.This transferred data may include lead and sensor identificationinformation stored by the transponder and used by IMD 12 to configurethe system in a manner to be discussed further below.

[0054] In one embodiment, transmitter/receiver 380 decodes data receivedfrom the transponder 262, and provides this data to digitalcontroller/timer circuit 330 for subsequent storage in RAM/ROM unit 314.The data may also be transmitted to an external programmer 420 (notshown in FIG. 5) via antenna 334. Digital controller/timer circuit 330may initiate an interrogation of the transponder following lead implantdetection via antenna 260. Lead implant detection may be performed asdescribed in U.S. Pat. No. 5,534,018 and 6,016,447 to Wahlstrand andJuran, respectively, incorporated herein by reference in theirentireties.

[0055] It may be noted that although FIG. 5 illustratestransmitter/receiver circuit 380 as being a separate circuit as comparedto transmitter/receiver 332, the two circuits may be included as asingle circuit providing both the ability to transfer and receive datato/from an outside device, and to further receive and/or transmit datafrom one or more transponders such as transponder 262.

[0056]FIG. 6 is a circuit block diagram illustrating in more detailexemplary components of transponder 262 and transmitter/receiver circuit380 of FIG. 5. Transmitter/Receiver 380 includes an energy source 390,which may be an inductive circuit, or a photoelectric or piezoelectrictransducer to generate electromagnetic, ultrasonic, or optical energy,respectively, as represented by line 391. This energy is received byenergy coupler 392, which generates the current and voltage levelsneeded to power the rest of transponder 262. Transponder includes acontrol circuit 393, which is coupled to a non-volatile storage device394. The non-volatile storage device may be a switch device, or anyother type of non-volatile storage device known in the art, including aread-only memory (ROM). One or more data values indicative of devicetype, device technical information, and/or device configurationinformation may be stored in storage device 394 and read by controlcircuit 393. The control circuit 393 provides this information totransmitter/receiver 395, which transmits the data via an RF or othertype of communication to transmitter/receiver 396. This transmission isindicated by line 397.

[0057] Transmitter/Receiver 380 further includes a transmitter/receiver396 that may provide an unmodulated carrier signal totransmitter/receiver 395. Transmitter/receiver 395 has a tuned resonantcircuit as discussed above for resonating at the frequency of thecarrier signal to re-transmit a signal at the carrier frequency. Thetransmitter/receiver 395 also includes means for superimposing aninformation signal on the re-transmitted signal by modulating thecarrier or harmonies of the carrier to reflect the information stored bystorage device 394. It may be noted that in an alternative embodiment,the signal provided by the transmitter/receiver 396 is used both as theenergy source and the carrier signal such that energy source 390 is notneeded.

[0058] In one embodiment of the invention, transmitter/receiver 395 maybe programmed with information from an external transmitter/receivercircuit at the time of manufacture. This information may include modeland serial numbers, lot numbers, expiration dates, electricalcharacteristics, labeling changes, cautions, product performanceresults, recall information, and shipping information such a freight IDsand the like. The transponder could further be programmed to storeintended therapy information, indications for use, and calibrationparameters. All, or portions of, associated technical manuals may bedownloaded to the transponder as permitted by the capacity of thestorage device.

[0059] If transponder is capable of receiving data from an externaldevice in the manner discussed above, data stored within the IMD may beloaded into storage device 394. For example, storage device 394 maystore the therapy settings and/or any programmable parameters used tocalibrate the IMD for a specific patient. These stored settings andparameters could then be automatically uploaded from transponder 362following a replacement procedure during which the patient receives anew IMD. This saves time, since manual intervention is not required toconfigure the newly-implanted device. Other information may likewise bedownloaded to transponder 362, including general patient information andhealth history, and information associated with drug therapies that mayor may not be coordinated with the therapy provided by the IMD. In oneembodiment, a physician may store information such as threshold values,lead or other impedance values, and/or additional operational anddiagnostic information that are determined either at the time ofimplant, or during subsequent patient visits.

[0060] Returning now to FIG. 5, use of the lead identification andconfiguration information is discussed further. Information from one ormore transponders such as transponder 262 may be obtained by theinput/output circuit 320 in the manner discussed above. This informationmay be stored in memory of the IMD such as memory within microcomputercircuit 302. The data may also be transferred to an external device forstorage with patient record data. This information may be analyzed bymicrocomputer circuit 302 or an external processor to automaticallyconfigure the IMD. For example, this data can be used by the processorto adjust gain/energy control circuit 348 in a manner that controls thegains of output amplifier circuit 340 and sense amplifiers 360. Theadjustments may be based on the type of leads and sensors that aredetected in the system. According to one aspect of the system, in theevent a particular lead or sensor is not present, unused functionswithin the IMD may be placed in a low-power mode to conserve batterypower.

[0061] The ability to adjust the gain associated with a sensed signal isimportant for several reasons. Physiological sensors such as pressure,temperature, oxygen saturation, or any of the other sensors types knownin the art to measure physiological parameters often have operatingparameters that vary widely. This is a result of variable conditionsthat occur during the manufacturing process, as well as differencesassociated with materials used during production. Therefore, differentsensors of the same type may have significantly different scale factors,offsets, and gains. One way to compensate for such variability involvesperforming a test at the time of implant. A physician may test sensoroperation and calibrate the sensor to account for the variable factors.A system and method for performing this type of calibration is describedin U.S. Pat. No. 5,919,221. This type of calibration procedure may betime-consuming and error prone, however.

[0062] According to the current invention, sensors may be tested at thetime of manufacture to determine specific operating parameters. Theseparameters may then be stored in transponder storage device 394, whichmay be carried on the sensor lead or the sensor itself. These parametersmay be transferred to an IMD in the manner discussed above for use inautomatically adjusting sensor gains to account for the sensordifferences, and may be further used to adjust and calibrate the IMDfunctions associated with the sensors. For example, sensor output couldbe calibrated if an active sensor is being utilized. Such parameters mayalso be used by a data processing system such as microcomputer 302 toadjust digital values derived from the measured sensor signals. Thiseliminates the need for human intervention.

[0063] Information gained from the transponder may also be used bycontroller/timer 330 to control selection circuits 361 and 341. Forexample, the signals provided to sense amplifiers 360 may be selected byselection circuit 361 based on the leads and/or sensors being used by aparticular system. Similarly, the signals that are driven by outputamplifier circuit 340 may be selected by selection circuit 341 based onwhether a lead or a particular electrode is available within the system,and is being used to provide therapy for a given patient. The selectioncircuits thereby provide “plug-and-play” capabilities for the IMDconnector block based on the devices that are sensed within the system.

[0064] Information provided by the transponder may further be used toselect the configuration of switchable circuits such as those describedin U.S. Pat. No. 4,665,919 to Mensink, incorporated herein by referencein its entirety. The configuration of the switchable circuits controlsone or more operating parameters of the device, such as input amplifierparameters and filter settings and sensitivity. This configuration canbe modified based on the type of components available within the systemas indicated by data stored in one or more of transponder circuits 362.

[0065] The uses of the configuration and calibration data discussedabove are exemplary only, and it will be understood that such data maybe used in many other ways to program or automatically calibrateelectronic circuitry associated with an IMD or an external device usedwith the IMD.

[0066]FIG. 7 is a system block diagram of additional embodiments of thepresent invention. Specifically, a bi-directional wirelesscommunications system between programmer 420, personal data management(PDM) unit 420′ and a number of implantable medical devices (IMDS)represented by IMD 410, IMD 410′ and IMD 410″ is shown. The IMDs areimplanted in patient 10 beneath the skin or muscle. The IMDs areelectrically coupled to electrodes 418, 430, and 436 respectively in amanner known in the art. IMD 410 may include a microprocessor fortiming, sensing and pacing functions consistent with preset programmedfunctions as discussed above. Similarly, IMDs 410′ and 410″ may bemicroprocessor-based to provide timing and sensing functions to executethe clinical functions for which they are employed. For example, IMD410′ could provide neural stimulation to the brain via electrode 430 andIMD 410″, and/or may function as a drug delivery system that iscontrolled by electrode 436.

[0067] The various functions of the IMDs may be coordinated usingwireless telemetry. Wireless links 442, 444 and 446 jointly andseverally couple IMDs 410, 410′ and 410″ such that programmer 420 maytransmit commands or data to any or all the of IMDs via one of telemetryantennas 428, 432 and 438. This configuration provides a highly flexibleand economical wireless communications system between the IMDS. Further,the structure provides a redundant communications system, which enablesaccess to any one of a multiplicity of IMDs in the event of amalfunction of one or two of antennas 428, 432 and 438.

[0068] Programming commands or data are transmitted from programmer 420to IMDs 410, 410′ and 410″ via external RF telemetry antenna 424.Telemetry antenna 424 may be an RF head or equivalent. Antenna 424 maybe located on programmer 420 externally on the case or housing.Telemetry antenna 424 is generally telescoping and may be adjustable onthe case of programmer 420. Both programmer 420 and PDM unit 420′ may beplaced a few feet away from patient 10 and would still be within rangeto wirelessly communicate with telemetry antennas 428, 432 and 438.

[0069] In one embodiment, a remote web-based expert data center 462 maybe accomplished through programmer 420 or PDM unit 420′. Accordingly,programmer 420 and PDM unit 420′ function as an interface between IMDs410, 410′ and 410″ and data center 462. One of the many distinguishingelements of the present invention includes the use of various scalable,reliable and high-speed wireless communication systems tobi-directionally transmit high fidelity digital/analog data betweenprogrammer 420 and data center 462.

[0070] There are a variety of wireless mediums through which datacommunications could be established between programmer 420 or PDM unit420′ and data center 462. The communications link between programmer 420or PDM unit 420′ and data center 462 could be modem 460, which isconnected both to programmer 420 and to data center 462.

[0071] Alternative data transmission systems include, withoutlimitations, stationary microwave and/or RF antennas 448 beingwirelessly connected to programmer 420 via tunable frequency wave 450,and with data center 462 via wireless link 465. Similarly, PDM unit420′, mobile vehicle 452, and satellite 456 are in communications withdata center 462 via similar wireless links. Further, mobile system 452and satellite 456 are in wireless communications with programmer 420 orPDM unit 420′ via tunable frequency waves 454 and 458, respectively.

[0072] In one embodiment, a telnet system may be used to wirelesslyaccess data center 462. Telnet emulates a client/server model andrequires that the client run dedicated software to access data center462. The telnet scheme may employ various operating systems includingUNIX, Macintosh, and all versions of Windows.

[0073] Using the system shown in FIG. 6, an operator at programmer 420or data center 462 may initiate remote contact with any of the implanteddevices via link antennas 428, 432 and 438 to enable data reception andtransmission. For example, an operator or a clinician at data center 462may downlink to programmer 420 to perform a routine evaluation ofprogrammer 420. If a downlink is required from programmer 420 to IMD 410for example, the downlink is affected using telemetry antenna 422. Inthe alternate, if an uplink is initiated from patient 10 to programmer420, the uplink is executed via wireless link 426.

[0074] Each antenna from the IMDs can be used to uplink all or one ofthe IMDs to programmer 420. For example, IMD 410″, which relates toneural implant 430, can be implemented to up-link, via wireless antenna434 or wireless antenna 434′, any one, two or more IMDs to programmer420. Preferably bluetooth or equivalent chips, adopted to functionwithin a body and which result in low current drain, are included in theIMD to provide wireless and seamless connections 442, 444 and 446between IMDs 410, 410′ and 410″. The communication scheme is designed tobe broadband compatible and capable of simultaneously supportingmultiple information sets and architecture, transmitting at relativelyhigh speed, to provide data, sound and video services on demand.

[0075] The various communication paths as shown in FIG. 6 allow leadidentification and sensor configuration data to be uploaded to eitherprogrammer 420, or to data center 462. Specifically, in the system ofFIG. 6, a transmitter/receiver such as transmitter/receiver 380 (FIG. 5)may be resident in programmer 420. This transmitter/receiver mayinterrogate transponders provided on one or more of the leads todetermine lead types, serial numbers, and any available sensorcalibration values in a manner similar to that described above. Thetransfer of information from the transponders may be performed usingdata encryption technology as described in the co-pending applicationentitled “Method and Apparatus to Secure Data Transfer from MedicalDevice Systems”, Ser. No. 09/431,881 filed Nov. 2, 1999 by Nichols andincorporated herein by reference. Information that is gained during theinterrogation may be entered and stored into a patient record eitherwithin the memory of programmer 420, or at data center 462. Theinformation may further be employed to configure one or more IMDfunctions or systems automatically based on lead types, and/or may alsobe used to calibrate sensor circuits in ways similar to those discussedabove.

[0076] In yet another embodiment, a transmitter/receiver such astransmitter/receiver 380 (FIG. 5) may instead be resident in PDM 420′.This transmitter/receiver may interrogate all lead componentsinterconnected to the various IMDs to determine lead types, serialnumbers, any sensor calibration values, and to communicate thisinformation to programmer 420. Programmer may then program any or all ofthe IMDs to properly configure the IMD configurations. Alternatively,this configuration function may be performed by the processing circuitassociated with each IMD.

[0077] The foregoing examples describe several embodiments of theinventive recognition and configuration system and method, although itwill be understood that modifications are possible within the scope ofthe current invention. For example, the foregoing examples discuss asystem that is powered using a remote energy source and an energycoupler as shown in FIG. 6. Other types of power systems may beutilized, however. In one instance, transponder 262 is not passive, butinstead receives power by loosely coupling off of electrical therapyoutput of an IMD.

[0078]FIG. 8 is a circuit diagram illustrating a transponder 498 coupledto the therapy output energy source of IMD 500. IMD 500 is shown coupledto a lead that includes two conductors 504 and 506. These conductors arecoupled to a bridge circuit that includes capacitor 508. This capacitoris charged by one or more pulse signals generated by IMD 500 during, forexample, the delivery of pacing therapies or other pulsed stimulationtherapies. The pulsed signals 509 include a position and a negativephase such that during a portion of the signal, the voltage at point 510is more position than at point 512, and in a different portion of thesignal, the voltage polarity is reverse. In the former instance, currentflows through diodes 514 and 516, and in the later instance currentflows through diodes 518 and 520. In both cases, capacitor 510 ischarged in the manner shown.

[0079] In the preferred embodiment, capacitor 510 is charged by theoccurrence of multiple pulsed signals. For example, ten or more pulsesmay be required to completely charge the capacitor. The values ofresistors 522 and 524 are selected to prevent the capacitor circuit frompresenting an unduly large load that would affect the therapy deliveryof IMD 500. Capacitors 526 and 528 may be provided to prevent a DCoffset voltage potential from being present across conductors 504 and506, which may promote corrosion of any electrodes that are carried bythe lead. Finally, it may be noted that if a unipolar lead is employed,the capacitor circuit is coupled to only a single lead conductor, withthe second connection being provided via the IMD and transponder cans,as indicated by dashed line 530.

[0080] Using the circuit of FIG. 8, transponder 498 may beintermittently operated to provide a brief burst of modulated RF energyfrom the transmitter of the transponder. In a similar manner, thereceiver of the transponder could be intermittently powered to receiveinformation from the IMD or another source. This embodiment would allowfor longer-range communications than is provided by thepassively-powered embodiment.

[0081] Another modification to the current invention involves use of asurface acoustic wave (SAW) filter 104 within the transponder as shownin FIG. 3. This type of filter includes an SAW delay line. An RF signalis transmitted from an interrogation unit such as transmitter/receivercircuit 380 of FIG. 6, and is received by an antenna residing in thetransponder that is coupled to the delay line. The signal is provided tothe delay line, which includes predetermined discontinuities that resultin signal reflections. The unique signal reflections, which are a resultof the selected configuration of the delay line, can be interpreted as asignature which may be transmitted to the interrogation unit forinterpretation. The signature may encode a serial number, or any othertype of information. The SAW filter thereby serves as a nonvolatilestorage device not unlike a hard-wired switch. This filter may be usedin place of, or in addition to, storage devices such as storage device394 of FIG. 6.

[0082] According to another aspect of the invention, data stored withina transponder 362 of a component is employed by an IMD to configurecircuitry within the component. For example, an embodiment of a lead mayinclude data interface to couple to an interface of the IMD. Based oninformation transferred from a transponder of the lead to the IMD, aprocessing circuit such as micro-computer circuit 302 is capable oftransferring signals via the data interface to configure circuitry ofthe lead. For example, the processing circuit may store data within aprogrammable device such as a register provided by the lead, therebyconfiguring the lead for operation with the IMD.

[0083] Other modifications are possible within the scope of the currentinvention. For example, although the above-described embodimentsprimarily relate to a transponder attached to, or integrated within, alead, the invention may be usefully employed to identify otherimplantable medical devices that may be used in conjunction with theactive IMD in the system. For example, pluggable antennas or electrodesthat may be selectively coupled to the active IMD may be identified andconfigured using a mechanism similar to that described herein.Additional components such as heart valves or stents could includesimilar transponders on the surface of, or integrated within, the deviceto store information that may then be transferred to external devicesthat are located within, or outside of, the body. Therefore, whileparticular embodiments of the present invention have been disclosed, itis to be understood that various different modifications are possibleand are contemplated within the scope of the specification, drawings,abstract and appended claims.

What is claimed is:
 1. A medical system, comprising: a first implantablemedical device (IMD) implanted within a patient having a firstcommunication circuit and storage means for storing data signalsdescriptive of the medical system; a second communication circuit inproximity to the first communication circuit to receive the data signalsfrom the first communication circuit; a second IMD implanted in thepatient; and a processing circuit coupled to receive the data signalsfrom the second communication circuit and to configure the second IMDbased on the data signals.
 2. The system of claim 1, wherein the secondcommunication circuit is carried within the second IMD.
 3. The system ofclaim 2, wherein the processing circuit is coupled to the secondcommunication circuit.
 4. The system of claim 1, wherein the secondcommunication circuit is external to the patient.
 5. The system claim 1,wherein the storage means includes means for storing informationdescriptive of at least one of the first and second IMDs, theinformation being selected from the group consisting of model and serialnumbers, lot numbers, expiration dates, electrical characteristics,labeling changes, cautions, product performance results, recallinformation, shipping information, freight IDs, intended therapyinformation, indications for use, and calibration parameters, technicalmanuals, therapy settings, threshold values, therapy settings andimpedance values.
 6. The system of claim 1, wherein the firstcommunication circuit includes a passive transponder, and wherein thesecond communication circuit includes a circuit to provide a signal topower the passive transponder.
 7. The system of claim 1, wherein thefirst communication circuit includes a circuit to receive power from thesecond IMD.
 8. The system of claim 1, wherein the first IMD includes asensor to sense a physiological parameter, and wherein the second IMDincludes sensor means for calibrating operation of the sensor based onthe data signals.
 9. The system of claim 1, wherein the first IMDincludes means for providing electrical stimulation to the patient, andwherein the second IMD includes means for calibrating a manner ofdelivery of the electrical stimulation based on the data signals. 10.The system of claim 1, wherein the second IMD is capable of performingmultiple functions, the second IMD further includes means for disablingone or more of the multiple functions based on the data signals.
 11. Thesystem of claim 1, wherein the first communication circuit includes areceiver capable of receiving signals from the second communicationcircuit.
 12. The system of claim 1, wherein the first IMD includes asurface acoustic wave (SAW) filter.
 13. The system of claim 1, whereinthe storage means stores operating parameters descriptive of the secondIMD.
 14. The system of claim 1, wherein the second IMD includesswitchable circuits, and wherein the processing circuit includes meansfor configuring the switchable circuits based on the data signals.
 15. Asystem to configure an implantable medical device (IMD), wherein the IMDis in communication with at least one additional component external tothe IMD, the system comprising: a first communication circuit carried onthe at least one additional component, the communication circuit tostore data signals descriptive of the at least one additional component;a second communication circuit in proximity to the first communicationcircuit to receive the data signals from the first communicationcircuit; and a processing circuit coupled to receive the data signalsfrom the second communication circuit, and to configure operations ofthe IMD based on the data signals.
 16. The system of claim 15, whereinthe first communication circuit is a transponder.
 17. The system ofclaim 16, wherein the transponder is a passive transponder.
 18. Thesystem of claim 15, wherein the transponder includes a storage circuitto store the data signals descriptive of the at least one additionalcomponent.
 19. The system of claim 15, wherein the storage circuitincludes a circuit to store ones of the data signals indicative ofcomponent identification information.
 20. The system of claim 15,wherein the storage circuit includes a circuit to store ones of the datasignals indicative of technical data associated with the at least oneadditional component.
 21. The system of claim 15, wherein the at leastone additional component is a sensor to sense a physiological parameter,and wherein the storage circuit includes a circuit to store ones of thedata signals descriptive of the sensor.
 22. The system of claim 15,wherein the at least one additional component is a lead, and wherein thestorage circuit includes a circuit to store ones of the data signalsindicative of connector information associated with the lead.
 23. Thesystem of claim 15, wherein the second communication circuit is locatedwithin the IMD.
 24. The system of claim 15, wherein the secondcommunication circuit is located in a device external to the IMD. 25.The system of claim 24, wherein the second communication circuit islocated in an external programmer.
 26. The system of claim 24, whereinthe second communication circuit is located in a patient data module(PDM).
 27. The system of claim 21, wherein the first communicationcircuit includes an RF transmitter.
 28. The system of claim 27, whereinthe first communication circuit includes an RF receiver capable ofreceiving information from the second communication circuit.
 29. Thesystem of claim 28, wherein the first communication circuit includes acircuit to allow the storage circuit to store the information receivedfrom the second communication circuit.
 30. The system of claim 15,wherein the first communication circuit includes a surface acoustic wave(SAW) filter.
 31. The system of claim 15, wherein the IMD includes atleast one amplification circuit, and wherein the system further includesa gain adjustment circuit coupled to control the gain of the at leastone amplification circuit, and wherein the processing circuit is capableof configuring the gain adjustment circuit based on the data signals.32. The system of claim 15, wherein the system further includes at leastone selection circuit coupled to the at least one additional component,and wherein the processing circuit is capable of configuring theselection circuit to control interconnection of the at least oneadditional component with the IMD based on the data signals.
 33. Thesystem of claim 21, wherein the system further includes a circuit toallow the processing circuit to calibrate the at least one sensor basedon the data signals.
 34. A method of configuring a medical system,comprising the steps of: (a) storing data signals in a first IMD; (b)providing a second IMD; (c) transferring the data signals from the firstIMD to a location outside of the first IMD; and (d) configuring thesecond IMD based on the data signals.
 35. The method of claim 34, andincluding: (a) providing a first communication circuit in the first IMD;(b) providing a second communication circuit proximal to the second IMD;and wherein step (c) including transferring the data signals from thefirst IMD to the second IMD via the first and second communicationcircuits.
 36. The method of claim 34, wherein the first IMD includes atleast one optional component, and wherein step (d) includes configuringthe second IMD to recognize the presence of the at least one optionalcomponent.
 37. The method of claim 34, wherein step (d) includesconfiguring the second IMD to optimally operate with circuits includedwithin the first IMD.
 38. The method of claim 34, wherein step (d)includes disabling one or more functions of the second IMD.
 39. Themethod of claim 35, wherein step (c) includes providing a signal to thefirst IMD to power the first communication circuit.
 40. The method ofclaim 34, wherein step (a) includes storing data signals in the firstIMD that are indicative of the operating parameters of the second IMD.41. The method of claim 34, wherein step (a) includes storing datasignals in the first IMD that are indicative of the operating parametersof the first IMD.
 42. The method of claim 34, wherein step (c) includestransferring the data signals from the first IMD to a programmer, andwherein step (d) includes configuring the second IMD via the programmer.